<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>NaN</title>
</head>
<body>
    <script>
       /*  console.log(NaN,typeof NaN);
        console.log(0/0,6/0,-6/0);
        consloe.log(Math.sqrt(-1));
        consloe.log("abc"-10);
        consloe.log(undefined + 10);
        console.log(parseInt("hello")) */
        const a = 0/0;
        const b  = parseInt("hello");
        if(parseInt("hello") ==NaN ){
            // 这段代码不会执行，因为它是false
            console.log("不是一个数字");
        }
        if(Number.isNaN(parseInt("hello"))){
            console.log("不是一个数字");
        }
        console.log(a==b);
    </script>
</body>
</html>